If you were having an operation to repair nerve damage would you need time off work?

It depends: Your question can not be answered the way you rised it.. There are to many unknown variables to account for, such as part of the body treated, nature of your work and daily tasks performed, your medical/mental status prior and after surgery, etc. It is your primary doctor's decision, even not a surgeon who operated on you. Go tp your primary doctor and be properly evaluated.

Possibly: There are many types of surgery to repair nerve damage. Time off from work depends on what the operation is being done. Minor surgery may need little time off (also depends on what type of work you do), while major reconstructions could require extended time off.

YES: Time off to rest after surgery is very important.